Marcello is a scruffy little dog who lives in a brown box outside of a small trattoria in Italy with his five brothers, seven sisters, four cousins, and two great aunts. The best part about his life is the plate of meatballs served by the trattoria's owner each day. Oh, how Marcello loves those meatballs. He dreams of those meatballs.

But one day, the allure of the meatballs leads him on an exciting adventure. He finds himself in a new home with a new owner and the scent of meatballs nearby. Marcello needs to sneak into the neighbor's house and get his paws on those delicious meatballs. He concocts a number of ill-fated plans to get what he wants.

Based on a real-life story, Marcello the Dog follows one dog's hijinks to fill his tummy with delicious meatballs.